Salesforce JavaScript Developer Practice Exam

What is an effect of using Object.assign() in JavaScript?

1. It creates a deep copy of an object

2. It merges multiple objects into one

3. It randomizes object properties

4. It encrypts the object data

The correct answer is: It merges multiple objects into one

Using Object.assign() indeed merges multiple objects into one, which is why that answer is the correct choice. When you pass one or more source objects as arguments to Object.assign(), it takes the enumerable own properties from those source objects and copies them into the target object. If the target object already has properties that are also present in the source objects, the values in the source objects will overwrite the existing values in the target object. This method is particularly useful for combining configurations and merging state objects in applications, allowing for a more dynamic approach to managing object properties. It’s important to note that Object.assign() does a shallow copy, meaning it only copies properties at the first level. If the properties being copied are objects themselves, only references to those objects are copied, not actual deep copies; hence, it does not create nested copies of object properties. The other options, such as creating a deep copy, randomizing properties, or encrypting data, do not accurately represent the function of Object.assign(). Understanding this function is essential for effectively manipulating and managing objects in JavaScript development.